Exhaust particulate filter

Abstract

A particulate filter for an exhaust system configured to receive an exhaust flow is disclosed. The filter includes a wall-flow filtration element having a first regeneration zone and a second regeneration zone, the first zone being downstream of the second zone, and a heat source disposed at the first regeneration zone. In response to demand for regeneration, the wall-filtration element regenerates according to a staged regeneration such that the first zone initiates regeneration ahead of the second zone, and each zone regenerates in the direction of the exhaust flow.

1. A particulate filter for an exhaust system configured to receive an exhaust flow, comprising:
 a wall-flow filtration particulate filter element having a first regeneration zone and a second regeneration zone, the first zone being downstream of the second zone, the first and second regeneration zones being part of the same wall-filtration particulate filter element; and 
 a heat source disposed at the first regeneration zone; 
 wherein in response to demand for regeneration, the wall-filtration element regenerates according to a staged regeneration such that the first zone initiates regeneration ahead of the second zone, and each zone regenerates in the direction of the exhaust flow. 
 
     
     
       2. The particulate filter of  claim 1 , wherein:
 the heat source comprises a catalyst. 
 
     
     
       3. The particulate filter of  claim 1 , wherein:
 the heat source comprises a heater. 
 
     
     
       4. The particulate filter of  claim 3 , wherein:
 the heater is an electric heater. 
 
     
     
       5. The particulate filter of  claim 1 , further comprising:
 a second heat source disposed at the second regeneration zone. 
 
     
     
       6. The particulate filter of  claim 1 , further comprising:
 a control configured to initiate heating at the heat source. 
 
     
     
       7. The particulate filter of  claim 1 , wherein the wall-flow filtration element comprises:
 a first end, a second end, and internal walls having pores defining a porosity sufficient to trap carbonaceous exhaust particulates; and 
 an inlet channel with an inlet port at the first end and a first end-plug at the second end, and an outlet channel with a second end-plug at the first end and an outlet port at the second end, the inlet channel being in fluid communication with the outlet channel via the internal walls; 
 wherein the internal walls define a first zone extending from the second end toward the first end a distance of about 25% to about 50% of the overall distance, and a second zone extending the remaining distance of about 50% to about 75% of the overall distance; and 
 wherein an oxidation catalyst is disposed on the internal walls of the first zone. 
 
     
     
       8. The particulate filter of  claim 7 , wherein the oxidation catalyst is disposed on the internal walls of the first zone but not the second zone. 
     
     
       9. The particulate filter of  claim 7 , wherein the oxidation catalyst comprises Cordierite. 
     
     
       10. The particulate filter of  claim 7 , wherein:
 the porosity of the first end-plug is greater than the porosity of the second end-plug. 
 
     
     
       11. A method for regenerating a particulate filter for an exhaust system configured to receive an exhaust flow, the particulate filter comprising a wall-flow filtration particulate filter element having a first regeneration zone and a second regeneration zone, the first zone being downstream of the second zone, the first and second regeneration zones being part of the same wall-filtration particulate filter element, the wall-flow filtration particulate filter element of the first zone being continuous with the wall-flow filtration particulate filter element of the second zone without interruption, and a heat source disposed at the first regeneration zone, the method comprising:
 in response to demand for regeneration, regenerating the wall-filtration element according to a staged regeneration such that the first zone initiates regeneration ahead of the second zone, each zone regenerates in the direction of the exhaust flow, and the regeneration progresses along the continuous particulate filter element defined by the wall-flow filtration particulate filter element of the first zone being continuous with the wall-flow filtration particulate filter element of the second zone. 
 
     
     
       12. The method of  claim 11 , wherein:
 the regeneration of the first zone comprises igniting deposited soot via an oxidation catalyst disposed at the first zone. 
 
     
     
       13. The method of  claim 12 , wherein:
 the regeneration of the second zone comprises igniting deposited soot in the absence of an oxidation catalyst disposed at the second zone. 
 
     
     
       14. The method of  claim 11 , wherein:
 the regeneration of the first zone comprises igniting deposited soot via a heater disposed proximate the first zone. 
 
     
     
       15. The method of  claim 14 , wherein:
 the regeneration of the second zone comprises igniting deposited soot via a heater disposed proximate the second zone. 
 
     
     
       16. The particulate filter of  claim 1 , wherein:
 the heat source is disposed at least partially along a length of the first regeneration zone. 
 
     
     
       17. The particulate filter of  claim 5 , wherein;
 the second heat source is disposed at least partially along a length of the second regeneration zone. 
 
     
     
       18. The particulate filter of  claim 1 , wherein:
 the wall-flow filtration element of both the first regeneration zone and the second regeneration zone is a particulate filter. 
 
     
     
       19. The particulate filter of  claim 1 , wherein:
 the wall-flow filtration particulate filter element of first zone is continuous with the wall-flow filtration particulate filter element of the second zone without interruption. 
 
     
     
       20. A method for regenerating a particulate filter for an exhaust system configured to receive an exhaust flow, the particulate filter comprising a wall-flow filtration element having a first regeneration zone and a second regeneration zone, the first zone being downstream of the second zone, and a heat source disposed at the first regeneration zone, the wall-flow filtration element further comprising a first end, a second end, and internal walls having pores defining a porosity sufficient to trap carbonaceous exhaust particulates, and an inlet channel with an inlet port at the first end and a first end-plug at the second end, and an outlet channel with a second end-plug at the first end and an outlet port at the second end, the inlet channel being in fluid communication with the outlet channel via the internal walls, wherein the internal walls define a first zone extending from the second end toward the first end a distance of about 25% to about 50% of the overall distance, and a second zone extending the remaining distance of about 50% to about 75% of the overall distance, and wherein an oxidation catalyst is disposed on the internal walls of the first zone, the method comprising:
 in response to demand for regeneration, regenerating the wall-filtration element according to a staged regeneration such that the first zone extending the distance of about 25% to about 50% of the overall distance initiates regeneration ahead of the second zone extending the remaining distance of about 50% to about 75% of the overall distance, and each zone regenerates in the direction of the exhaust flow.